Natural gas has been cast by some as an eco-friendly alternative to coal because of its lower carbon emissions, but natural gas power plants themselves aren’t all that efficient. GE on Wednesday announced a natural gas power plant design that is more efficient than the standard, and allows grid and power plant operators to better manage power supply and demand, and integrate natural gas power with clean power.
The FlexEfficiency 50 design can convert 61 percent of the energy in every cubic foot of natural gas into electricity and ramp up power production at a rate of 50 MW per minute. The design is a departure from what power plants usually do today, delivering either high efficiencies or speedy power ramp-up rates, but not usually both, said Paul Browning, VP of thermal products at GE Energy.
GE previously offered power plants that could achieve 60-percent efficiency, but those designs couldn’t offer the quick ramp-up rates that will become more critical with the growing amount of wind and solar electricity flowing to the grid, Browning said. At the same time, GE previously also offered power plants that can boost production quickly but can operate only at 46-percent efficiency. The low efficiency is because of the use of simple-cycle combustion turbines.
Combined-cycle power plants are more cutting-edge and efficient because they reuse the waste heat from gas turbines to generate power. GE is borrowing from a jet engine design that allows the pilot to change the thrust level of the airplane quickly to boost the ramp-up rate for a combined cycle power plant, Browning said.
Boosting electricity output quickly has always been crucial for responding to the fluctuating demand of the power grid, particularly when demand spikes because, say, people are cranking up their air conditioning during a particularly hot day. But power plants can’t run at full blast right after they are turned on.
The need to be able to ramp-up quickly becomes even more critical with the addition of renewable energy such as wind and solar. The production of wind and solar electricity is dependent on when the wind blows or the sun shines, so neither can deliver a steady supply of power to the grid around the clock. Yet the grid must maintain a balance of supply and demand in order to run smoothly. Grid operators and utilities across the country have wrestled with the challenge of integrating wind and solar electricity into the power supply without disrupting the grid.
“With 1 percent or 2 percent of renewables, it’s not an issue. But at 5 percent to eventually 33 percent or 40 percent, then it becomes an enormous challenge,” Browning said. California has a mandate to buy 33 percent of its electricity from renewable sources by 2020.
GE is a formidable player in the power plant engineering business, from the fossil fuel varieties to wind power. The company is tackling the solar power business in earnest and last month, announced a plan to build a 400 MW factory to build solar panels using cadmium-telluride, the same type of solar panels made by First Solar. GE has made it clear it wants to not only make solar panels but also engineer solar power plants.
Image courtesy of GE